Add a device config for actively preferring bad wifi

Test: FrameworksNetTests
      adb shell device_config put connectivity actively_prefer_bad_wifi
       + check that dumpsys updates
Test: at this patchset tests fail with :
      Permission denial: reading from settings requires:android.permission.READ_DEVICE_CONFIG

Change-Id: Icfe1e64b8313921ff1dc8e4cbd45f967692e1c4a
diff --git a/service/src/com/android/server/ConnectivityService.java b/service/src/com/android/server/ConnectivityService.java
index 1236243..84cf561 100755
--- a/service/src/com/android/server/ConnectivityService.java
+++ b/service/src/com/android/server/ConnectivityService.java
@@ -5112,22 +5112,32 @@
 
         pw.println("Bad Wi-Fi avoidance: " + avoidBadWifi());
         pw.increaseIndent();
-        pw.println("Config restrict:   " + configRestrict);
-        pw.println("Actively prefer:   " + activelyPreferBadWifi());
+        pw.println("Config restrict:               " + configRestrict);
+        pw.println("Actively prefer bad wifi:      " + activelyPreferBadWifi());
 
-        final String value = mMultinetworkPolicyTracker.getAvoidBadWifiSetting();
+        final String settingValue = mMultinetworkPolicyTracker.getAvoidBadWifiSetting();
         String description;
         // Can't use a switch statement because strings are legal case labels, but null is not.
-        if ("0".equals(value)) {
+        if ("0".equals(settingValue)) {
             description = "get stuck";
-        } else if (value == null) {
+        } else if (settingValue == null) {
             description = "prompt";
-        } else if ("1".equals(value)) {
+        } else if ("1".equals(settingValue)) {
             description = "avoid";
         } else {
-            description = value + " (?)";
+            description = settingValue + " (?)";
         }
-        pw.println("User setting:      " + description);
+        pw.println("Avoid bad wifi setting:        " + description);
+        final Boolean configValue = mMultinetworkPolicyTracker.deviceConfigActivelyPreferBadWifi();
+        if (null == configValue) {
+            description = "unset";
+        } else if (configValue) {
+            description = "force true";
+        } else {
+            description = "force false";
+        }
+        pw.println("Actively prefer bad wifi conf: " + description);
+        pw.println();
         pw.println("Network overrides:");
         pw.increaseIndent();
         for (NetworkAgentInfo nai : networksSortedById()) {
diff --git a/service/src/com/android/server/connectivity/MultinetworkPolicyTracker.java b/service/src/com/android/server/connectivity/MultinetworkPolicyTracker.java
index a36bf4b..58196f7 100644
--- a/service/src/com/android/server/connectivity/MultinetworkPolicyTracker.java
+++ b/service/src/com/android/server/connectivity/MultinetworkPolicyTracker.java
@@ -32,6 +32,7 @@
 import android.net.Uri;
 import android.os.Build;
 import android.os.Handler;
+import android.provider.DeviceConfig;
 import android.provider.Settings;
 import android.telephony.SubscriptionManager;
 import android.telephony.TelephonyCallback;
@@ -41,6 +42,7 @@
 import com.android.connectivity.resources.R;
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.modules.utils.build.SdkLevel;
+import com.android.net.module.util.DeviceConfigUtils;
 
 import java.util.Arrays;
 import java.util.List;
@@ -67,6 +69,9 @@
 public class MultinetworkPolicyTracker {
     private static String TAG = MultinetworkPolicyTracker.class.getSimpleName();
 
+    // See Dependencies#getConfigActivelyPreferBadWifi
+    public static final String CONFIG_ACTIVELY_PREFER_BAD_WIFI = "actively_prefer_bad_wifi";
+
     private final Context mContext;
     private final ConnectivityResources mResources;
     private final Handler mHandler;
@@ -82,6 +87,43 @@
     private volatile long mTestAllowBadWifiUntilMs = 0;
 
     /**
+     * Dependencies for testing
+     */
+    @VisibleForTesting
+    public static class Dependencies {
+        /**
+         * @see DeviceConfigUtils#getDeviceConfigPropertyInt
+         */
+        protected int getConfigActivelyPreferBadWifi() {
+            // CONFIG_ACTIVELY_PREFER_BAD_WIFI is not a feature to be rolled out, but an override
+            // for tests and an emergency kill switch (which could force the behavior on OR off).
+            // As such it uses a -1/null/1 scheme, but features should use
+            // DeviceConfigUtils#isFeatureEnabled instead, to make sure rollbacks disable the
+            // feature before it's ready on R and before.
+            return DeviceConfig.getInt(DeviceConfig.NAMESPACE_CONNECTIVITY,
+                    CONFIG_ACTIVELY_PREFER_BAD_WIFI, 0);
+        }
+
+        /**
+         @see DeviceConfig#addOnPropertiesChangedListener
+         */
+        protected void addOnDevicePropertiesChangedListener(@NonNull final Executor executor,
+                @NonNull final DeviceConfig.OnPropertiesChangedListener listener) {
+            DeviceConfig.addOnPropertiesChangedListener(DeviceConfig.NAMESPACE_CONNECTIVITY,
+                    executor, listener);
+        }
+
+        @VisibleForTesting
+        @NonNull
+        protected Resources getResourcesForActiveSubId(
+                @NonNull final ConnectivityResources resources, final int activeSubId) {
+            return SubscriptionManager.getResourcesForSubId(
+                    resources.getResourcesContext(), activeSubId);
+        }
+    }
+    private final Dependencies mDeps;
+
+    /**
      * Whether to prefer bad wifi to a network that yields to bad wifis, even if it never validated
      *
      * This setting only makes sense if the system is configured not to avoid bad wifis, i.e.
@@ -129,15 +171,17 @@
         }
     }
 
-    public MultinetworkPolicyTracker(Context ctx, Handler handler) {
-        this(ctx, handler, null);
+    public MultinetworkPolicyTracker(Context ctx, Handler handler, Runnable avoidBadWifiCallback) {
+        this(ctx, handler, avoidBadWifiCallback, new Dependencies());
     }
 
-    public MultinetworkPolicyTracker(Context ctx, Handler handler, Runnable avoidBadWifiCallback) {
+    public MultinetworkPolicyTracker(Context ctx, Handler handler, Runnable avoidBadWifiCallback,
+            Dependencies deps) {
         mContext = ctx;
         mResources = new ConnectivityResources(ctx);
         mHandler = handler;
         mAvoidBadWifiCallback = avoidBadWifiCallback;
+        mDeps = deps;
         mSettingsUris = Arrays.asList(
                 Settings.Global.getUriFor(NETWORK_AVOID_BAD_WIFI),
                 Settings.Global.getUriFor(NETWORK_METERED_MULTIPATH_PREFERENCE));
@@ -166,8 +210,11 @@
         mContext.registerReceiverForAllUsers(mBroadcastReceiver, intentFilter,
                 null /* broadcastPermission */, mHandler);
 
+        final Executor handlerExecutor = new HandlerExecutor(mHandler);
         mContext.getSystemService(TelephonyManager.class).registerTelephonyCallback(
-                new HandlerExecutor(mHandler), new ActiveDataSubscriptionIdListener());
+                handlerExecutor, new ActiveDataSubscriptionIdListener());
+        mDeps.addOnDevicePropertiesChangedListener(handlerExecutor,
+                properties -> reevaluateInternal());
 
         reevaluate();
     }
@@ -201,7 +248,7 @@
         // NETWORK_AVOID_BAD_WIFI setting.
         if (allowBadWifi) return true;
 
-        return getResourcesForActiveSubId()
+        return mDeps.getResourcesForActiveSubId(mResources, mActiveSubId)
                 .getInteger(R.integer.config_networkAvoidBadWifi) == 0;
     }
 
@@ -223,7 +270,7 @@
         // bad wifi (only stay stuck on it if already on there). This implementation treats
         // any non-0 value like 1, on the assumption that anybody setting it non-zero wants
         // the newer behavior.
-        return 0 != getResourcesForActiveSubId()
+        return 0 != mDeps.getResourcesForActiveSubId(mResources, mActiveSubId)
                 .getInteger(R.integer.config_activelyPreferBadWifi);
     }
 
@@ -237,13 +284,6 @@
         reevaluateInternal();
     }
 
-    @VisibleForTesting
-    @NonNull
-    protected Resources getResourcesForActiveSubId() {
-        return SubscriptionManager.getResourcesForSubId(
-                mResources.getResourcesContext(), mActiveSubId);
-    }
-
     /**
      * Whether we should display a notification when wifi becomes unvalidated.
      */
@@ -255,6 +295,29 @@
         return Settings.Global.getString(mResolver, NETWORK_AVOID_BAD_WIFI);
     }
 
+    /**
+     * Returns whether device config says the device should actively prefer bad wifi.
+     *
+     * {@see #configActivelyPrefersBadWifi} for a description of what this does. This device
+     * config overrides that config overlay.
+     *
+     * @return True on Android U and above.
+     *         True if device config says to actively prefer bad wifi.
+     *         False if device config says not to actively prefer bad wifi.
+     *         null if device config doesn't have an opinion (then fall back on the resource).
+     */
+    public Boolean deviceConfigActivelyPreferBadWifi() {
+        if (SdkLevel.isAtLeastU()) return true;
+        switch (mDeps.getConfigActivelyPreferBadWifi()) {
+            case 1:
+                return Boolean.TRUE;
+            case -1:
+                return Boolean.FALSE;
+            default:
+                return null;
+        }
+    }
+
     @VisibleForTesting
     public void reevaluate() {
         mHandler.post(this::reevaluateInternal);
@@ -276,7 +339,12 @@
         mAvoidBadWifi = settingAvoidBadWifi || !configRestrictsAvoidBadWifi();
 
         final boolean prevActive = mActivelyPreferBadWifi;
-        mActivelyPreferBadWifi = configActivelyPrefersBadWifi();
+        final Boolean deviceConfigPreferBadWifi = deviceConfigActivelyPreferBadWifi();
+        if (null == deviceConfigPreferBadWifi) {
+            mActivelyPreferBadWifi = configActivelyPrefersBadWifi();
+        } else {
+            mActivelyPreferBadWifi = deviceConfigPreferBadWifi;
+        }
 
         return mAvoidBadWifi != prevAvoid || mActivelyPreferBadWifi != prevActive;
     }
@@ -285,10 +353,8 @@
      * The default (device and carrier-dependent) value for metered multipath preference.
      */
     public int configMeteredMultipathPreference() {
-        // TODO: use R.integer.config_networkMeteredMultipathPreference directly
-        final int id = mResources.get().getIdentifier("config_networkMeteredMultipathPreference",
-                "integer", mResources.getResourcesContext().getPackageName());
-        return mResources.get().getInteger(id);
+        return mDeps.getResourcesForActiveSubId(mResources, mActiveSubId)
+                .getInteger(R.integer.config_networkMeteredMultipathPreference);
     }
 
     public void updateMeteredMultipathPreference() {
diff --git a/tests/integration/src/com/android/server/net/integrationtests/ConnectivityServiceIntegrationTest.kt b/tests/integration/src/com/android/server/net/integrationtests/ConnectivityServiceIntegrationTest.kt
index 5b3f37d..26b058d 100644
--- a/tests/integration/src/com/android/server/net/integrationtests/ConnectivityServiceIntegrationTest.kt
+++ b/tests/integration/src/com/android/server/net/integrationtests/ConnectivityServiceIntegrationTest.kt
@@ -211,10 +211,15 @@
         doReturn(TestNetIdManager()).`when`(deps).makeNetIdManager()
         doReturn(mock(BpfNetMaps::class.java)).`when`(deps).getBpfNetMaps(any(), any())
         doAnswer { inv ->
-            object : MultinetworkPolicyTracker(inv.getArgument(0), inv.getArgument(1),
-                    inv.getArgument(2)) {
-                override fun getResourcesForActiveSubId() = resources
-            }
+            MultinetworkPolicyTracker(inv.getArgument(0),
+                    inv.getArgument(1),
+                    inv.getArgument(2),
+                    object : MultinetworkPolicyTracker.Dependencies() {
+                        override fun getResourcesForActiveSubId(
+                            connResources: ConnectivityResources,
+                            activeSubId: Int
+                        ) = resources
+                    })
         }.`when`(deps).makeMultinetworkPolicyTracker(any(), any(), any())
         return deps
     }
diff --git a/tests/unit/java/com/android/server/ConnectivityServiceTest.java b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
index e1208ef..7993a5c 100755
--- a/tests/unit/java/com/android/server/ConnectivityServiceTest.java
+++ b/tests/unit/java/com/android/server/ConnectivityServiceTest.java
@@ -29,7 +29,6 @@
 import static android.Manifest.permission.NETWORK_SETTINGS;
 import static android.Manifest.permission.NETWORK_STACK;
 import static android.Manifest.permission.PACKET_KEEPALIVE_OFFLOAD;
-import static android.Manifest.permission.READ_DEVICE_CONFIG;
 import static android.app.PendingIntent.FLAG_IMMUTABLE;
 import static android.content.Intent.ACTION_PACKAGE_ADDED;
 import static android.content.Intent.ACTION_PACKAGE_REMOVED;
@@ -366,6 +365,7 @@
 import com.android.server.connectivity.ClatCoordinator;
 import com.android.server.connectivity.ConnectivityFlags;
 import com.android.server.connectivity.MultinetworkPolicyTracker;
+import com.android.server.connectivity.MultinetworkPolicyTrackerTestDependencies;
 import com.android.server.connectivity.Nat464Xlat;
 import com.android.server.connectivity.NetworkAgentInfo;
 import com.android.server.connectivity.NetworkNotificationManager;
@@ -1634,12 +1634,7 @@
         volatile int mConfigMeteredMultipathPreference;
 
         WrappedMultinetworkPolicyTracker(Context c, Handler h, Runnable r) {
-            super(c, h, r);
-        }
-
-        @Override
-        protected Resources getResourcesForActiveSubId() {
-            return mResources;
+            super(c, h, r, new MultinetworkPolicyTrackerTestDependencies(mResources));
         }
 
         @Override
@@ -5810,16 +5805,12 @@
     public void testPreferBadWifi_doNotPrefer() throws Exception {
         // Starting with U this mode is no longer supported and can't actually be tested
         assumeFalse(SdkLevel.isAtLeastU());
-        runAsShell(READ_DEVICE_CONFIG, () -> {
-            doTestPreferBadWifi(false /* preferBadWifi */);
-        });
+        doTestPreferBadWifi(false /* preferBadWifi */);
     }
 
     @Test
     public void testPreferBadWifi_doPrefer() throws Exception {
-        runAsShell(READ_DEVICE_CONFIG, () -> {
-            doTestPreferBadWifi(true /* preferBadWifi */);
-        });
+        doTestPreferBadWifi(true /* preferBadWifi */);
     }
 
     @Test
diff --git a/tests/unit/java/com/android/server/connectivity/MultinetworkPolicyTrackerTest.kt b/tests/unit/java/com/android/server/connectivity/MultinetworkPolicyTrackerTest.kt
index 8348675..b52e8a8 100644
--- a/tests/unit/java/com/android/server/connectivity/MultinetworkPolicyTrackerTest.kt
+++ b/tests/unit/java/com/android/server/connectivity/MultinetworkPolicyTrackerTest.kt
@@ -27,6 +27,7 @@
 import com.android.server.connectivity.MultinetworkPolicyTracker.ActiveDataSubscriptionIdListener
 import android.os.Build
 import android.os.Handler
+import android.os.test.TestLooper
 import android.provider.Settings
 import android.telephony.SubscriptionInfo
 import android.telephony.SubscriptionManager
@@ -47,7 +48,6 @@
 import org.junit.runner.RunWith
 import org.mockito.ArgumentCaptor
 import org.mockito.ArgumentMatchers.anyInt
-import org.mockito.ArgumentMatchers.argThat
 import org.mockito.Mockito.any
 import org.mockito.Mockito.doCallRealMethod
 import org.mockito.Mockito.doReturn
@@ -55,6 +55,8 @@
 import org.mockito.Mockito.times
 import org.mockito.Mockito.verify
 
+const val HANDLER_TIMEOUT_MS = 400
+
 /**
  * Tests for [MultinetworkPolicyTracker].
  *
@@ -91,8 +93,11 @@
         Settings.Global.putString(resolver, NETWORK_AVOID_BAD_WIFI, "1")
         ConnectivityResources.setResourcesContextForTest(it)
     }
-    private val handler = mock(Handler::class.java)
-    private val tracker = MultinetworkPolicyTracker(context, handler)
+    private val csLooper = TestLooper()
+    private val handler = Handler(csLooper.looper)
+    private val trackerDependencies = MultinetworkPolicyTrackerTestDependencies(resources)
+    private val tracker = MultinetworkPolicyTracker(context, handler,
+            null /* avoidBadWifiCallback */, trackerDependencies)
 
     private fun assertMultipathPreference(preference: Int) {
         Settings.Global.putString(resolver, NETWORK_METERED_MULTIPATH_PREFERENCE,
@@ -146,6 +151,18 @@
         }
         // In all cases, now the system actively prefers bad wifi
         assertTrue(tracker.activelyPreferBadWifi)
+
+        // Remaining tests are only useful on T-, which support both the old and new mode.
+        if (SdkLevel.isAtLeastU()) return
+
+        doReturn(0).`when`(resources).getInteger(R.integer.config_activelyPreferBadWifi)
+        assertTrue(tracker.updateAvoidBadWifi())
+        assertFalse(tracker.activelyPreferBadWifi)
+
+        // Simulate update of device config
+        trackerDependencies.putConfigActivelyPreferBadWifi(1)
+        csLooper.dispatchAll()
+        assertTrue(tracker.activelyPreferBadWifi)
     }
 
     @Test
@@ -164,6 +181,8 @@
         Settings.Global.putString(resolver, NETWORK_METERED_MULTIPATH_PREFERENCE,
                 MULTIPATH_PREFERENCE_PERFORMANCE.toString())
 
+        assertTrue(tracker.avoidBadWifi)
+
         val listenerCaptor = ArgumentCaptor.forClass(
                 ActiveDataSubscriptionIdListener::class.java)
         verify(telephonyManager, times(1))
@@ -171,10 +190,6 @@
         val listener = listenerCaptor.value
         listener.onActiveDataSubscriptionIdChanged(testSubId)
 
-        // Check it get resource value with test sub id.
-        verify(subscriptionManager, times(1)).getActiveSubscriptionInfo(testSubId)
-        verify(context).createConfigurationContext(argThat { it.mcc == 310 && it.mnc == 210 })
-
         // Check if avoidBadWifi and meteredMultipathPreference values have been updated.
         assertFalse(tracker.avoidBadWifi)
         assertEquals(MULTIPATH_PREFERENCE_PERFORMANCE, tracker.meteredMultipathPreference)
diff --git a/tests/unit/java/com/android/server/connectivity/MultinetworkPolicyTrackerTestDependencies.kt b/tests/unit/java/com/android/server/connectivity/MultinetworkPolicyTrackerTestDependencies.kt
new file mode 100644
index 0000000..744c020
--- /dev/null
+++ b/tests/unit/java/com/android/server/connectivity/MultinetworkPolicyTrackerTestDependencies.kt
@@ -0,0 +1,47 @@
+package com.android.server.connectivity
+
+import android.content.res.Resources
+import android.net.ConnectivityResources
+import android.provider.DeviceConfig
+import android.provider.DeviceConfig.NAMESPACE_CONNECTIVITY
+import android.provider.DeviceConfig.OnPropertiesChangedListener
+import com.android.internal.annotations.GuardedBy
+import com.android.server.connectivity.MultinetworkPolicyTracker.CONFIG_ACTIVELY_PREFER_BAD_WIFI
+import java.util.concurrent.Executor
+
+class MultinetworkPolicyTrackerTestDependencies(private val resources: Resources) :
+        MultinetworkPolicyTracker.Dependencies() {
+    @GuardedBy("listeners")
+    private var configActivelyPreferBadWifi = 0
+    // TODO : move this to an actual fake device config object
+    @GuardedBy("listeners")
+    private val listeners = mutableListOf<Pair<Executor, OnPropertiesChangedListener>>()
+
+    fun putConfigActivelyPreferBadWifi(value: Int) {
+        synchronized(listeners) {
+            if (value == configActivelyPreferBadWifi) return
+            configActivelyPreferBadWifi = value
+            val p = DeviceConfig.Properties(NAMESPACE_CONNECTIVITY,
+                    mapOf(CONFIG_ACTIVELY_PREFER_BAD_WIFI to value.toString()))
+            listeners.forEach { (executor, listener) ->
+                executor.execute { listener.onPropertiesChanged(p) }
+            }
+        }
+    }
+
+    override fun getConfigActivelyPreferBadWifi(): Int {
+        return synchronized(listeners) { configActivelyPreferBadWifi }
+    }
+
+    override fun addOnDevicePropertiesChangedListener(
+        e: Executor,
+        listener: OnPropertiesChangedListener
+    ) {
+        synchronized(listeners) {
+            listeners.add(e to listener)
+        }
+    }
+
+    override fun getResourcesForActiveSubId(res: ConnectivityResources, id: Int): Resources =
+            resources
+}